Miscarriage: do I tell my partner?

I have been with my partner for four years now and are very serious. Early on in our relationship I had a miscarriage (didnt know i was pregnant) but did not tell him, I am not sure why but I was young and didnt know what to do! More and more over the past year I feel like I want to tell him!

However its been so long since it happened and I am worried about his reaction to why I didnt tell him sooner! And how to even bring it up in conversation? Or should I just not tell him as it was years ago....

Help please. Thanks for reading!